Liquid crystal alignment agent and liquid crystal alignment film formed therefore and manufacturing method thereof

Abstract

The present invention provides a free radical polymerizable liquid crystal alignment agent having superior coating ability, a manufacturing method, which comprises the process of coating the liquid crystal alignment agent onto a substrate, carrying out dehydration/ring-closure and free radical polymerization, enables obtaining a liquid crystal alignment film with superior reliability, superior voltage holding ratio and easy control of pretilt angle, and enables the manufacture of a liquid crystal display element provided with a liquid crystal alignment film. The free radical polymerizable liquid crystal alignment agent comprises a molecular compound containing at least 2 polymerizable maleamic acid groups and an organic solvent.

What is claimed is: 
     
         1 . A method of forming a liquid crystal alignment film comprising a process of coating a liquid crystal alignment agent onto a substrate, and then processing said alignment agent with dehydration/ring-closure reaction and free radical polymerization, wherein said liquid crystal alignment agent comprises a molecular compound containing at least 2 polymerizable maleamic acid groups (A), and an organic solvent (B). 
     
     
         2 . The method of forming a liquid crystal alignment film as claimed in  claim 1 , wherein said molecular compound containing at least 2 polymerizable maleamic acid groups (A) comprises a compound (A-1) represented by the following Formula (1), 
       
         
           
           
               
               
           
         
         wherein Q comprises a functional group represented by the following Formula (2); T is a structure selected from an aliphatic, an alicyclic and an aromatic hydrocarbon group; R 1  and R 2  are hydrogen atoms or alkyl groups having 1 to 8 carbon atoms and may be the same or different; m is an integer of 1 or more; and n is an integer of 2 or more,
   Formula (2) 
   R 3 —L—
 
 
         wherein L is a divalent organic group selected from the group consisting of single bond, —O—, —CO—, —COO—, —OCO—, —NHCO—, —CONH—, —S—, methylene group, alkylene group having 2 to 6 carbon atoms and phenylene group; and R 3  is a monovalent organic group selected from the group consisting of an alkyl group having 6 to 30 carbon atoms, an alicyclic or aromatic or a heterocyclic ring skeleton having 4 to 40 carbon atoms and a fluoroalkyl group having 6 to 12 carbon atoms. 
       
     
     
         3 . The method of forming a liquid crystal alignment film as claimed in  claim 2 , wherein said compound (A-1) comprises a compound represented by the following Formula (3). 
       
         
           
           
               
               
           
         
       
     
     
         4 . The method of forming a liquid crystal alignment film as claimed in  claim 2 , wherein said molecular compound containing at least 2 polymerizable maleamic acid groups (A) further comprises a compound (A-2) represented by the following Formula (7), 
       
         
           
           
               
               
           
         
         wherein T is a structure selected from an aliphatic, an alicyclic and an aromatic hydrocarbon group; R 1  and R 2  are hydrogen atoms or alkyl groups having 1 to 8 carbon atoms and may be the same or different; and n is an integer of 2 or more. 
       
     
     
         5 . The method of forming a liquid crystal alignment film as claimed in  claim 1 , wherein said liquid crystal alignment agent further comprises a molecular compound containing at least 2 epoxy groups.